I’ve tried different clients: Element web, desktop, and android, and FluffyChat desktop and android. The problems seems to come, as other have written, when the matrix.org server is involved: it’s people from their handle there which experience glitches joining rooms in other servers. It seems this “part” of the fediverse still needs a lot of development.
Agree 110%! It’s sad because it pushes back those people who were curious about alternatives and were willing to try. Hopefully things will improve with time…